In this application, funding is requested for a MoFlo(TM) fluorescence activated cell sorter (FACS) to be located in the Biosafety Level 3 (BL-3) containment laboratory of the Gladstone Institute of Virology and Immunology at the San Francisco General Hospital (SFGH) and University of California, San Francisco (UCSF). The proposed FACS will augment the capabilities of the Gladstone FACS Core Laboratory, a recharge unit that has been in operation for the past four years and which offers flow cytometry services for multiple users in the Bay Area and elsewhere. The existing FACSVantage sorter in this Core has inherent limitations which present significant obstacles for the successful completion of currently-funded and projected NIH research. The capabilities of the proposed MoFlo(TM) FACS significantly exceed those provided by the existing instrument, both in terms of speed and in the ability to precisely identify multiple cell populations. The proposed FACS will permit viable sorting of both human cells (treated as potentially infectious with HW-1 or other human pathogens) and non- human cells. At present, with the exception of the FACS Core Laboratory at Gladstone, no other cell sorters in San Francisco can be used to separate live human cells due to the lack of appropriate safety equipment There are also no available sorting facilities in this area which offer the throughput and multiparameter capabilities of the MoFlo(TM). Thus, this new instrument will significantly strengthen and enhance the research capacity of many NIH-funded investigators at Gladstone, at UCSF, and elsewhere (e.g., members of the AIDS Clinical Trials Group). The requested FACS will be critical for the successful pursuit of a broad range of projects, reflecting the scientific interests and expertise of the selected major users, including: 1) T-cell kinetics in HIV-infected individuals; 2) the effects of HIV on hematopoiesis; 3) functional analysis of immune restoration in HIV patients receiving HAART; 4) HHV-8 pathogenesis; 5) development of novel animal models for the study of HIV; 6)trafficking of maternal cells into the fetal circulation; 7) immunity against HPV in HIV-infected individuals;, 8) chemokine regulation of integrin activity; 9) SIV viral evolution; and 10) modulation of CD8 T-cell function by HIV env protein. In summary, this proposed instrument is pivotal to the success of the research of multiple NIH- funded projects, will provide a critical resource to the research community in the Bay Area and elsewhere, and should spark innovative research in the future.